1. Field
The present disclosure relates to Global Navigation Satellite System (GNSS) devices and, more specifically, to surveying using a GNSS device.
2. Related Art
Navigation receivers that use global navigation satellite systems, such as GPS or GLONASS (hereinafter collectively referred to as “GNSS”), enable a highly accurate determination of the position of the receiver. The satellite signals may comprise carrier signals that are modulated by pseudo-random binary codes and that, on the receiver side, may be used to measure the delay relative to a local reference clock. These delay measurements may be used to determine the pseudo-ranges between the receiver and the satellites. The pseudo-ranges are not true geometric ranges because the receiver's local clock may be different from the satellite onboard clocks. If the number of satellites in sight is greater than or equal to four, then the measured pseudo-ranges can be processed to determine the user's single point location as represented by a vector X=(x,y,z)T, as well as to compensate for the receiver clock offset.
Surveyors may use GNSS devices to measure points representing boundaries between plots of land, paths to be traversed, and the like. Typically, the surveyor may traverse a boundary or path to be surveyed and may use a GNSS device to measure and record the locations of points along the way. Processing software may then be used to plot the measured points to generate a computer representation of the boundary or path. For example, to survey the closed rectangular boundary of plot of land 100 shown in FIG. 1, the surveyor may first walk to point 101 to measure and record the location of the point. The surveyor may then proceed to measure and record the locations of points 103, 105, and 107. However, since the boundary of plot 100 has a closed shape, the surveyor may be required to return to point 101 to measure and record the location of the point. Based on the order that the points were recorded, processing software may be used to connect points 101 and 103, 103 and 105, 105 and 107, and 107 and 101, as shown in FIG. 1.
While this technique can be used to define any desired closed shape, problems may occur if the measured locations for junctions (e.g., points requiring multiple measurements), such as point 101, are not identical. In particular, the processing software may incorrectly connect the measured points, thereby generating incorrect boundaries for the plot of land. For instance, if the second measurement of point 101 does not match the first measurement of point 101, the processing software may generate a line having four segments rather than the closed rectangular shape shown in FIG. 1. These measurement inconsistencies can be caused by the user positioning the GNSS device at slightly different positions for each junction measurement and/or measurement errors of the GNSS device.